1. Field of the Invention
The present invention relates to a Group III nitride compound semiconductor light-emitting element and particularly to a Group III nitride compound semiconductor light-emitting element in which the wavelength of light emitted from a light-emitting layer is converted so that light in a color different from the color of the light emitted from the light-emitting layer can be emitted. The light-emitting element according to the invention can be used, for example, for a polychromatic light source or a white light source.
2. Description of the Related Art
There is known a light-emitting element or a light-emitting device (LED) of the type which uses a Group III nitride compound semiconductor light-emitting element and a fluorescent substance in combination so that the fluorescent substance can convert the wavelength of a part of light emitted from a light-emitting layer contained in the light-emitting element to thereby emit light in a color different from the original color of light emitted from the light-emitting element. For example, an LED of the type has been already put into practical use. In the LED of this type, a Group III nitride compound semiconductor light-emitting element for emitting blue light, and a fluorescent substance for emitting yellow light when excited by the blue light are used in combination so that white light can be emitted. The LED of this type is generally formed so that the light-release side of the Group III nitride compound semiconductor light-emitting element is coated with a light-transmissive resin containing a fluorescent substance.
To produce the related-art LED, it was necessary to first produce a light-emitting element, and then coat the light-emitting element with a fluorescent substance-containing resin. That is, the production process was troublesome and complex, and the production cost was high.
Moreover, because the light-emitting element was coated with the fluorescent substance-containing resin generally by means of application, dipping or the like, it was not easy to control the thickness of the resin accurately. For this reason, the amount of the fluorescent substance to be added varied easily, so that it was not easy to produce the LED with uniform quality (emission color, emission intensity, and so on).
Moreover, because the fluorescent substance was disposed in a position far from a light-emitting portion (light-emitting layer) in the light-emitting element, and because a part of light emitted from the light-emitting element was consumed wastefully as a loss in the interface of the fluorescent substance-containing resin, light could not be always emitted with high efficiency from the fluorescent substance. For this reason, the light-emitting efficiency of the LED was low.